External Appearance

Visually, the Power Zone 850W CM PSU is certainly unique. Plastic frames cover the front and rear sides of the unit, while the series logo is embossed on the sides of the black chassis. The fan guard is not a typical circular grill but instead uses an array of parallel wires. A metallic badge is placed above the fan's engine, denoting the unit's maximum power output, and the sticker with the electrical specifications can be seen on the top of the chassis.

The visual enhancements however also add bulk, making the chassis 175mm deep, considerably deeper than a typical ATX PSU, thus the Power Zone 850W CM is incompatible with a large number of PC cases. The plastic frames also add spacing around the main PSU chassis, which is why be quiet! includes longer screws than normal.

For the cabling, this is a fully modular design, with no hardwired cables. Many modular PSUs will have hardwired 24-pin and ATX12V/EPS12V cables as these are always required, but by making a fully modular case it opens the door for shorter cable harnesses. Unfortunately be quiet! doesn't currently sell any shorter cable sets for the Power Zone series, but that may change.

Internal Design

One of this product's most important features is the use of a "Silent Wings" 135mm fan. These fans have been designed by be quiet! with ribbed blades that are supposed to reduce aerodynamic noise; however, this particular model is not very quiet, as it has a maximum speed of 2900RPM. It takes a very efficient 850 Watt unit to allow the use of a low-speed cooling fan, and with a Bronze rating this particular line benefits from better airflow and cooling. The fan does use a high quality fluid dynamic bearing, which will help to reduce noise, but as we'll see in a moment the PSU is still clearly audible at higher loads.

The OEM behind the Power Zone 850W CM is Fortron Source, a company we usually find behind middle and lower range products. This PSU uses a textbook filtering stage, with four Y capacitors, two X capacitors, and two filtering inductors at the back of the receptacle and on the main board. Two primary rectification bridges work in parallel, each bolted onto its own small heatsink next to the large APFC coil. The two 220 μF APFC capacitors are rated for operation at 105 °C and are supplied by Teapo. Actually, almost every single capacitor in the Power Zone 850W CM, electrolytic and polymer alike, is supplied by Teapo, with the weird exception of a single small Nippon Chemi-Con electrolytic capacitor on the distribution PCB.

Strangely, although the platform has very good potential and implements modern technologies, such as an Active Clamp topology and DC-to-DC conversion circuits, be quiet! uses very basic active components (i.e. transistors) on the primary inversion and secondary conversion levels. This reduces the overall efficiency of the Power Zone 850W CM down to 80 Plus Bronze levels. If they would have chosen active components with lower resistance and/or better behavior, this design could easily qualify for 80 Plus Silver or Gold status.

The assembly quality of the Power Zone 850W CM is excellent, especially for a Fortron Source design. It is a clean design, with black glue used to mechanically secure the components and minimize high frequency vibration noises. The soldering job is not perfect, as we found a few joints where the use of solder was a bit too generous, but it is very good nonetheless.

My 8 year old PC Power Cooling 750 Quad uses an ancient design with an 80mm fan and I don't think the fan has ever exceeded 1500RPM (~36db) so anything modern should exceed this, especially for $160. As said, Seasonic, Superflower, and one of my favorite budget PSU OEM's, FSP, are all considerably better options at this price.

Fortron (Sparkle) are pretty good PSU's but I wouldn't spend more than $40 on one as a low-watt office PC replacement.Reply

Have you ever actually had your PSU at >90% load? Comparing your PSU at a load significantly below max to a second one at full load isn't a fair comparison.

What does surprise me is that the fan speed curve on this one appears to be linear. The last time I was shopping for PSUs (a few years ago); most of the ones I saw that showed a fan curve kept the fan at it's minimum speed (or completely off?) for the bottom part of the load curve and only started ramping the speed when it got within 250-300W of max power, mostly relying on passive cooling below that point. I've used that observation for sizing PSUs to a target size of MaxLoad+250W so the fan never spins up adding to system noise.Reply

As a gamer who assembles their own systems, I make a conscious effort to never buy any component that's explicitly marketed "for gamers" - with the sole exception being the graphics card, of course.

This review just underlines once again why that practice is a good practice. Here we have a gamer-targeted product that's too highly powered for the average modern gamer PC, offers only mediocre efficiency and performance, errs on the side of unnecessarily hefty cooling and mounts an unreasonable price tag... and the biggest selling point is a different looking outer shell.

My own PSU is from be quiet!, too. But it's not from this gamer-targeted Power Zone series. No, I chose a Straight Power E9 series part with a wattage rating suitable for a single-GPU system. It is practically inaudible even under load, is rated 80PLUS Gold, was tested for excellent voltage regulation and, get this... cost only half the price of the unit tested in this review.

There are far too many reviews for these high-powered PSUs when most people are only running a single GPU. Too many neophyte gamers think they need 750W+ when most can easily get by on 400-550W.

We really need more reviews showing the practical power needs of a typical gaming system, and then focus on the PSUs to power them. Just because lower-output PSUs are lower in price doesn't mean we should spend an inordinate amount of time reviewing the higher-powered ones with the higher price tags. Sadly, the "quality" that may or may not be in a mfg's higher-powered PSU doesn't always trickle down to their lower-output models, so it would be good to highlight the ones that are or aren't quality choices at the lower to mid-range.Reply

Do I qualify if I also have a i7-3960X? Probably. But if I'm re-encoding and streaming video in the background while I play a visually-intensive game, I'd rather not have my power supply be the bottleneck. 140 W from my video card and 200 W from my CPU don't really add up to 750W.

But maybe I want another card? Especially with AMD CPU buyers, that scenario is common: a desire for upgradeability encourages the $30 for a higher-wattage power supply, as opposed to paying $50 for the 500W then another $80 for the 750W.

Sidenote: given how low the power consumption of Intel CPUs has gotten I'm surprised more manufacturers haven't considered supporting 4x 6pin or even 2x 6pin + 2x 8pin configurations on 550W and 60W PSUs. Connector count, in many cases, can drive the new system builder to the higher-wattage power supplies.Reply

I think they tend to err on the side of caution since they'd take the blame if someone did overload one; and they can't assume people will only use them with cards that barely need a 6+6 or barely need a 6+8 configuration.

4x 6 pin at 600W might be OK, since that'd be 2x 225W GPUs + 100W CPU/mobo + 50W drives/fans/etc = 600W total; but 4x6 GPU power connectors on a 550W PSU could go over the limit easily enough. 2x6 and 2x8 would on 600W would be even worse since that's promising enough power to run a pair of 300W GPUs.Reply

A good 750W PSU is good enough for even a dual SLI 780Ti system. At 550W, even a demanding single GPU system should have more than an adequate supply of power.

However in practice, some people buy these larger PSUs for two reasons:1) Possibility of future expansion. When I bought my PC last summer, I purchased a larger wattage PSU because I was still debating whether or not to get a second PSU. I haven't yet, but if I decide to, I already have enough power.2) PSUs generally get their best efficiency while running at 50-60% load. So having a 750W PSU to power a 400W system provides the best efficiency. (Granted I realize for many this is a silly point, since the extra cost of the PSU itself generally will outweigh any cost savings, but maybe they like to be green, or just have the money)Reply